1. Field of Invention
The present invention relates to transformers. More particularly, the present invention relates to coil modules and transformers which use the coil modules.
2. Description of Related Art
Coil elements are widely used in transformers and other electronic devices. However, coiling procedures often take too much time and become too complicated. Besides, implicit dangers such as accidental fires or electronic shocks might occur because of incautious manufacturing or usage.
Please refer to FIG. 1(a), which shows a schematic cross-sectional view of a traditional transformer 10 and coils thereon. The transformer 10 has a bobbin 101, pins 102, a metal core 103, insulation tapes 104, 105, and coils 106.
The bobbin 101 supports the pins 102 and the metal core 103. The insulation tapes 104 are used so that the positions of the coils 106 follow certain safety standards. The coils 106 are coiled in sequence one after another until all necessary coils 106 are installed on the bobbin 101. Each coil 106 has two wires connected to the pin 102 for connecting to other elements in certain applications. The tapes 105 are provided so that the coils 106 of different sets keep proper distance.
Please refer to FIG. 1 (b), which shows a schematic, cross-sectional view of another traditional transformer 11. Similarly, the transformer 11 has a bobbin 111, pins 112, a core 113, insulation layers 114 and coils 116.
The bobbin 111 supports the pins 112, the core 113, and the insulation layers 114. The coils 116 are coiled on the bobbin 111, one layer after another. In this example, four coil layers 1161, 1162, 1163, 1164 have different coil loops for performing two sets of electric voltage transformation. The coil layers 1161 and 1163 are used to function as primary coils of the transformer 11 for inputting electric voltage, and the layers 1162 and 1164 are used to function as secondary coils of the transformer 11 for outputting the resultant electric voltage.
The coiling procedures in both examples in FIG. 1(a) and FIG. 1(b) are slow because the coil wires are wound one layer after another. Incautious operators in a factory may make mistakes regarding loop number of coils for some layers. However, coils of other layers need to be unwound first before correcting the loop number of coils of the faulty layer.
Such coiling methods are also imprecise. In the example of FIG. 1(a), the thickness of tapes 104 and 105 are difficult to control. In FIG. 1(b), the insulation layers 114 take up unnecessary space and increase the size of the transformer 11. Also, coil wires may have different lengths even if the coil loops are the same when the coils are not neatly wound. Besides, coils are easily broken or fractured during winding, particularly when the bobbin structure is complicated like the one 111 shown in FIG. 1(b).
Therefore, there are still many problems for manufacturing transformers.
As seen from the above description, there is a strong need for flexible and reliable coil elements and transformer. An embodiment of the present invention provides a coil module. The coil module has a conductive wire and an insulating encapsulator. The conductive wire has a portion wound into coils. The loop number of the coils is selected from a predetermined set. The coils define a coil opening. The insulating encapsulator encapsulates the coils and defines a core opening. An outline of the core opening is within the coil opening.
A metal core is provided for manufacturing a transformer. Next, coil modules of necessary coil loops are selected. These coil modules are installed so that the core opening of the coil module surrounds the metal core. Besides, these coil modules are arranged as a stack. The coils of two adjacent coil modules are separated by the insulating encapsulators of the two adjacent coil modules.
The procedure of manufacturing transformers is therefore simplified and flexible. Furthermore, the coil modules are stacked directly so that the height of the transformer is reduced. The insulating encapsulator also protects the coils from damage by manufacturing or usage. Therefore, the present invention provides a nice solution for coiling in transformers that is flexible, improves quality and has low manufacturing cost.